1. Field of the Invention
One or more aspects of the present invention relate to voice coils and micro speakers using the voice coils, and more particularly, to voice coils using a surface mount technology (SMT) for connection with an electrode and SMT micro speakers using the voice coils.
2. Description of the Related Art
A speaker is an audio device for generating a sound wave. The sound wave is generated as follows. In a magnetic circuit including a plate, a magnet and a yoke, a voice coil adhered to a diaphragm is positioned in a gap between the plate and the yoke. When an electrical signal flows through the voice coil, the electrical signal is converted into kinetic energy so that the diaphragm generates a compression wave, thereby generating the sound wave.
As shown in FIGS. 1 and 2, a conventional micro speaker 10 used in portable electrical products such as cellular phones includes a diaphragm 11 for generating a sound by using a vibration, a voice coil 12 that is adhered to the diaphragm 11 and vibrates the diaphragm 11 when a current flows through the voice coil 12, a frame 13 for supporting the diaphragm 11, a U-shaped yoke 14 installed on an inner portion of the frame 13, a magnet 15 and a plate 16 which are adhered to a central portion of the U-shaped yoke 14, and a cover 17. A power leader line 12a of the voice coil 12 is adhered to the diaphragm 11 by adhesives 18, and simultaneously, is connected to an external contact electrode by using a soldering method. Thus, the voice coil 12 may be connected to a printed circuit board (PCB) of an electrical device.
The diaphragm 11 of the conventional micro speaker 10 is formed of a synthetic resin to have a thickness from several microns to several tens of microns. When a current flows through the voice coil 12 disposed on a central portion of the diaphragm 11, a magnetic line of force is generated from the voice coil 12, and thus the magnetic line of force interacts with the magnet 15. Due to the interaction between the magnetic line of force and the magnet 15, the voice coil 12 vibrates up and down according to a direction and frequency of the current flowing through the voice coil 12, and the diaphragm 11 fixed to an upper portion of the voice coil 12 also moves up and down so as to output a sound.
A conventional speaker is manufactured using a manual operation involving positioning and shaping of leader lines and electrodes of voice coils, thereby causing environmental contamination and lowering productivity. In addition, a soldered portion between a contact electrode and a power leader line of a voice coil may come apart due to vibration of a diaphragm.